DELETE

Function

DELETE deletes rows that satisfy the WHERE clause from the specified table. If the WHERE clause is absent, the effect is to delete all rows in the table. The result is a valid, but an empty table.

Precautions

• You must have the DELETE permission on the table to delete from it, as well as the SELECT permission for any table in the USING clause or whose values are read in the condition.
• For column-store tables, the RETURNING clause is currently not supported.

Syntax

Delete ::= [ WITH [ RECURSIVE ] with_query [, ...] ]
DELETE [/*+ plan_hint */] [ FROM ] [ ONLY ] table_name [ * ] [ [ AS ] alias ]
    [ USING using_list ]
    [ WHERE condition | WHERE CURRENT OF cursor_name ]
    [ RETURNING { * | { output_expr [ [ AS ] output_name ] } [, ...] } ];

Parameter Description

• WITH [ RECURSIVE ] with_query [, …]

  Specifies one or more subqueries that can be referenced by name in the main query, which is equivalent to a temporary table.

  If RECURSIVE is specified, it allows a SELECT subquery to reference itself by name.

  Format of with_query:

  with_query_name ::= with_query_name [ ( column_name [, ...] ) ] AS
  ( {select | values | insert | update | delete} )

  • with_query_name specifies the name of the result set generated by a subquery. Such names can be used to access the subquery result set.
  • column_name specifies the column name displayed in the subquery result set.
  • Each subquery can be a SELECT, VALUES, INSERT, UPDATE or DELETE statement.

• plan_hint clause

  Follows the DELETE keyword in the /*+ */ format. It is used to optimize the plan of a DELETE statement block. For details, see Hint-based Tuning. In each statement, only the first /*+ _plan_hint _*/ comment block takes effect as a hint. Multiple hints can be written.

• ONLY

  If ONLY is specified before the table name, matching rows are deleted from the named table only. If ONLY is not specified, matching rows are also deleted from any tables inheriting from the named table.

• table_name

  Specifies the name (optionally schema-qualified) of the target table.

  Value range: an existing table name

• alias

  Specifies a substitute name for the target table.

  Value range: a string. It must comply with the naming convention rule.

• using_list

  Specifies the USING clause.

• condition

  Specifies an expression that returns a Boolean value. Only rows for which this expression returns true will be deleted.

• WHERE CURRENT OF cursor_name

  This parameter is reserved.

• output_expr

  Specifies an expression to be computed and returned by the DELETE statement after each row is deleted. The expression can use any column names of the table. Write ***** to return all columns.

• output_name

  Specifies a name to use for a returned column.

  Value range: a string. It must comply with the naming convention rule.

Examples

-- Create the tpcds.customer_address_bak table.
mogdb=# CREATE TABLE tpcds.customer_address_bak AS TABLE tpcds.customer_address;

-- Delete employees whose ca_address_sk is smaller than 14888 from the tpcds.customer_address_bak table.
mogdb=# DELETE FROM tpcds.customer_address_bak WHERE ca_address_sk < 14888;

-- Delete all data from the tpcds.customer_address_bak table.
mogdb=# DELETE FROM tpcds.customer_address_bak;

Delete the tpcds.customer_address_bak table.
mogdb=# DROP TABLE tpcds.customer_address_bak;

Suggestions

• delete

  To delete all records in a table, use the truncate syntax.